The invention relates to a cooling apparatus for energy stores, in particular for motor vehicles, and to an energy store system as well as a motor vehicle having a cooling apparatus of this type.
Defined thermal management of the batteries/battery cells/battery cell modules is required to safeguard the range, service life and performance available for electric and hybrid vehicles. Here, it is decisive to keep the temperature spread between the cells and cell modules within the high voltage store as low as possible. Active and passive cooling systems are used for this purpose.
Increasing requirements made of the range and performance require, for example, an increasing number of cells which are connected in series and/or in parallel. As a result, the dimensions of the high voltage stores in the vehicle increase. This increases the challenge to achieve a more homogeneous cooling action over the entire dimension.
It is an object of the present invention to achieve more homogeneous cooling of the individual cell modules. This and other objects are achieved by way of a cooling apparatus for energy stores, an energy store system, and a motor vehicle equipped with the cooling apparatus, in accordance with embodiments of the invention.
In accordance with one exemplary embodiment of the invention, a cooling apparatus for energy stores is provided, in particular for motor vehicles, having a plurality of separate cooling modules for absorbing heat from the energy store, through which cooling modules refrigerant can flow, and which cooling modules have in each case one inlet and outlet; a common feed line, from which the respective inlets of the cooling modules branch, and a common discharge line, into which the respective outlets of the cooling modules open. This exemplary embodiment affords the advantage of modular construction. For example, the individual cooling modules can be identical and, depending on the vehicle type/energy store type, a suitable number of connected cooling modules are used which together form the cooling apparatus. The production costs can be reduced by way of a modular construction of this type. Cooling paths which are connected in parallel are configured by virtue of the fact that the individual cooling modules are attached to the common feed line. A more uniform distribution to the cooling modules which are connected in parallel can be achieved as a result. This has advantageous effects on the range, service life and performance of electric and hybrid vehicles. Here, the parallel paths can correspond, for example, to the electric connection of the cells and/or cell modules, since the waste heat which is produced in paths which are connected electrically in parallel is comparable.
In accordance with a further exemplary embodiment of the invention, expansion members are arranged in the respective inlets. By virtue of the fact that the expansion members are arranged in the respective inlets, the refrigerant upstream of the expansion members, that is to say in the common feed line, is held at a high pressure level. Therefore, the distribution to the individual inlets into the cooling modules takes place at a high pressure level, that is to say within a high pressure range, as a result of which a more homogeneous distribution to the cooling modules which are connected in parallel can be achieved. This has the advantage that high temperature spreads between the refrigerant paths which are connected in parallel (the cooling modules which are connected in parallel) can be avoided, and therefore a more uniform temperature level of all energy store modules and energy store cells within the high voltage store can be achieved. More homogeneous cooling is achieved by way of this homogeneous distribution of the refrigerant to a large number of individual parallel paths, which can improve the range, service life and performance of electric and hybrid vehicles. If the distribution took place after the expansion of the refrigerant, a homogeneous distribution would be difficult on account of the low quantity of residual liquid.
In accordance with a further exemplary embodiment of the invention, the expansion members are electric expansion valves, thermal expansion valves or throttles.
In accordance with a further exemplary embodiment of the invention, the expansion members are at the same time shut-off valves. A shut-off valve at an inlet of the common feed line can be dispensed with as a result.
According to a further exemplary embodiment of the invention, the expansion members with a shut-off function are throttling solenoid valves or thermostatic expansion valves.
In accordance with a further exemplary embodiment of the invention, a shut-off valve for interrupting the refrigerant flow is provided in the common feed line upstream of the first inlet and/or downstream of the last outlet. In particular, the shut-off valve is a solenoid valve. In addition to an interruption of the flow, for example in order to switch the cooling function of the cooling apparatus on and off, a shut-off valve affords the advantage that the cooling can be cycled and regulated.
In accordance with a further exemplary embodiment of the invention, the cooling modules have a plurality of flat tubes which are arranged in one plane and are connected to one another at their longitudinal ends by way of header tubes. In particular, all of the flat tubes of a cooling module are connected in series to one another by way of the header tubes, with the result that the refrigerant can flow through them one after another.
In accordance with a further exemplary embodiment of the invention, the common feed line and the common discharge line are configured separately from one another. In particular, the common feed line and the common discharge line are configured in each case by way of a separate tube line.
In accordance with a further exemplary embodiment of the invention, the common feed line and the common discharge line are configured within one line, the feed line and the discharge line being separated from one another by way of a dividing wall which runs in the longitudinal direction of the line.
In accordance with a further exemplary embodiment of the invention, the cooling modules are arranged in a flat and overlap-free manner.
In accordance with a further exemplary embodiment of the invention, the cooling modules are of identical configuration.
In accordance with a further exemplary embodiment of the invention, a heat exchanger is provided downstream of the last outlet, which heat exchanger is configured for separating liquid and gaseous components of the refrigerant.
In accordance with a further exemplary embodiment of the invention, a discharge line for the gaseous components is connected to an inlet of a compressor. This has the advantage that gas can be fed to the compressor as far as possible without liquid components. This is advantageous for the operation of the compressor.
In accordance with a further exemplary embodiment of the invention, a wall of the heat exchanger, which wall is covered with the liquid components during operation, is connected to the common feed line in a thermally conducting manner. This has the advantage that the temperature of the refrigerant in the common feed line is lowered and the temperature of the liquid components in the heat exchanger is increased. The efficiency of the cooling apparatus is increased by way of the temperature reduction in the common feed line. Superheating of the fluid which enters into the heat exchanger is ensured by way of the temperature increase of the liquid components in the heat exchanger, as a result of which an improved separation of gaseous and liquid components can be realized.
In accordance with a further exemplary embodiment of the invention, the expansion members are provided in pairs, two expansion members being provided within a single component with a fluid inlet, both expansion members being connected to the same fluid inlet. This has the advantage that a distribution of the refrigerant is carried out before the expansion and therefore on the liquid side, as a result of which a more homogeneous distribution can be realized.
Moreover, the invention relates to an energy store system having an energy store and a cooling apparatus in accordance with any of the preceding exemplary embodiments.
Moreover, the invention relates to a motor vehicle having a cooling apparatus of this type or an energy store system of this type.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.